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package br.unisc.pdaapp.meta;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

/**
 * This file is abstract to ensure that it can not be instantiated.
 *
 * @author guilherme
 */
public abstract class FileUtil
{

    /**
     * This method has been taken from:
     * http://www.exampledepot.com/egs/java.io/File2ByteArray.html
     *
     * The method also has been modified by me.
     * You can contact me by gui.jfrantz@gmail.com
     *
     * @param file
     * @return
     * @throws java.io.IOException
     */
    public static byte[] getBytesFromFile(File file) throws IOException
    {
        InputStream is = new FileInputStream(file);

        // Get the size of the file
        long length = file.length();

        // You cannot create an array using a long type.
        // It needs to be an int type.
        // Before converting to an int type, check
        // to ensure that file is not larger than Integer.MAX_VALUE.
        if (length > Integer.MAX_VALUE)
        {
            throw new IOException("File is too large");
        }

        // Create the byte array to hold the data
        byte[] bytes = new byte[(int) length];

        // Read in the bytes
        int offset = 0;
        int numRead = 0;
        while (offset < bytes.length && (numRead = is.read(bytes, offset, bytes.length - offset)) >= 0)
        {
            offset += numRead;
        }

        // Ensure all the bytes have been read in
        if (offset < bytes.length)
        {
            throw new IOException("Could not completely read file " + file.getName());
        }

        // Close the input stream and return bytes
        is.close();
        return bytes;
    }
}
